1. Field of the Invention
The invention relates to heat-stable fruit fillings for pastry products and to pastry products containing such fruit fillings. The invention also relates to a process for preparing such fruit fillings.
2. Prior Art
Fruit fillings or flavored jellies incorporated into pastry doughs are well known in the art. For example, U.S. Pat. No. 3,676,151 (Scharschmidt) is an example of a disclosure of a fruit filling designed to be incorporated into a dough. The dough is then oven baked. The finished product is stored until ready for use, at which time it is placed in a toaster. A difficulty with such product is that its filler is not heat-stable. If the pastry dough is not adequately sealed, the filler has a tendency to run out when heated thus playing havoc with the toaster, to say nothing of the loss of the filler. Such patent teaches the use of a combination of apple powder and invert syrup, which is a mixture of dextrose and fructose, but the proportions are low. Such patent also uses a high percentage of granular sugar. U.S. Pat. No. 3,833,741 (Katz et al.) teaches the production of a heat-stable filling by production of a two-phase filling, that is, a disperse phase of relatively small fat globules suspended in a polar matrix composed of protein, water and a mono or disaccharide. Heat coagulable proteins, such as, soy, and even gelatin are used as a heat stabilizing ingredient--such patent asserts having produced a filler that resists flow upon being heated. The process of preparation for such a filling requires the application of considerable external heat. For example, in a typical preparation, the mixture is heated to 110.degree. to 120.degree. F. The heat is necessitated because such patent uses a considerable portion of fat in its preparation.
U.S. Pat. No. 3,892,871 (Cooper) discloses that a superior jelly can be produced by the use of a corn syrup having a high fructose content with substantially no other sugar present except that derived from corn syrup. The jellies are made from corn syrup containing at least 15 percent of high fructose corn syrup, a natural fruit flavor, pectin (or modified pectin) and an acidifying agent. Pectin is a gelling agent. In the examples, the ratio of high fructose corn syrup (71 percent solids) to pectin is as high as 59.2 (or more) to one. However, such patent teaches the use of pectin, e.g., apple pectin, rather than apple powder as such. Additionally, such patent uses heat under vacuum to produce the gelling effect.
U.S. Pat. No. 3,867,560 (Menzi et al.) teaches dietetic confectioneries that are prepared from an aqueous homogeneous paste prepared from a mixture containing at least one assimilable carbohydrate selected from the group consisting of monosaccharides and oligosaccharides (in a proportion of from 35 to 60 percent by weight), at least one assimilable protein material soluble or dispersible in an aqueous medium of a pH between 6.2 and 7.2 (in a proportion of between 1 to 45 percent by weight), at least one gelling agent which is a gelling protein and a gelling carbohydrate, and between 4 and 24 percent by weight of water. The gelling agent contains at least 70 percent by weight of non-assimilable material. The entire amount of the gelling agent in the entire quantity of the mixture is between 12 and 20 percent by weight. Menzi et al. teaches the use of a high fructose corn syrup as the assimilable carbohydrate. In one embodiment, the mixture can contain 12 to 40 weight percent of the gelling agent and a powdery vegetable cellulose material, such as, apple marc. In the examples, the paste (used for the dietetic confectioneries) has a maximum ratio of fructose (as a syrup containing 70 percent by weight of dry materials) to apple marc powder of 1.89 to 1. An important ingredient of the patent product is a foamable protein, or else the mixture is preferably heated to 85.degree. to 100.degree. C.
U.S. Pat. No. 4,234,611 (Kahn et al.) discloses one of the more recent products adapted for a wide variety of uses including pastry filling. While such patent teaches a high fructose syrup and apples, it does not preclude the use of granular sugars or fat. The apples appear to be used solely as a fruit source. Starch is also an ingredient and the essence of the invention of such patent appears to be the production of a microbiologically stable food which can be kept at freezer or room temperature for extended periods. The application of heat is necessary in the preparation of such fillers.
U.S. Pat. No. 4,390,550 (Kahn et al.) teaches the production of fruit which is added to cereal. The fruit is first treated with sugar solution to remove part of the water thereof and then treated with a bath containing sugar solutes and a high fructose corn syrup. The examples teach apple pie fillings containing, among other things, dextrose-fructose syrup and frozen sliced apples. Example 4 discloses an apple donut filling containing, among other things, 11.40 parts of dehydrated apple pieces and 50.36 parts of dextrose-fructose syrup. The filling was cooked at 195.degree. F. for 5 to 10 minutes.
U.S. Pat. No. 4,387,109 (Kahn et al.) discloses oil-in-water emulsion foods which are best stored in a frozen state. Fructose is incorporated into the food to minimize crystallization at low temperatures. Along the same lines see U.S. Pat. No. 4,313,967 (Kahn et al.).
U.S. Pat. No. 2,359,228 (Lloyd et al.) discloses a cream filling for baked goods using a non-crystalline dried corn syrup which mainly contains dextrose, maltose and dextrines.
U.S. Pat. No. 2,059,541 (Thompson et al.) discloses jelly preparations for confectioners' products. The jelly preparations include pectin and acid constituents plus cane sugar, fruit pulp and glucose or invert sugar. Some of the preparations include corn syrup at a level less than the pectin level. The preparations are cooked at a temperature above the boiling point of water.
Pectins yield galactose, arabinose, and a sugar acid (galacturonic acid) upon hydrolysis. They are present in fruits and berries. In the presence of sucrose and small amounts of acids they form jellies. Thus there are three probable causes for failure of a jelly to gel: (1) insufficient pectin; (2) insufficient acid (usually sufficient acid is present in the fruit); or (3) insufficient sucrose. The concentration of sucrose is increased in jelly making by boiling off a portion of the water present. The concentration of pectin can be increased by adding a commercial solution of that substance. See Arnow, L. Earle, "Introduction To Physiological And Pathological Chemistry," The C. V. Mosby Company, (1961), p. 250.
DeMan, John M., "Principles Of Food Chemistry," The Avi Publishing Company, Inc., (1980), pp. 163 and 164, deals with pectin. Pectic substances are polymers of 1 to 4 linked- galacturonic acid existing in different degrees of esterification or neutralization. In addition pectin contains branched L-arabinan and 1 to 4 linked .beta.-D-galactan. Two factors are of great importance in determining the properties of pectins, especially gel formation: these are chain length and degree of esterification. Completely esterified pectins would have 16 percent of methoxyl content but do not occur in nature; the usual range is 9 to 12 percent of ester methoxyl, although some pectins may have a very low methyl content. When the methyl ester group is removed by alkaline hydrolysis or enzyme action a number of intermediates named pectinic acids are formed. When all of the methyl groups are removed the product becomes insoluble and is called pectic acid. Pectin is thus only a generic name for a range of products of widely differing composition which can be classified as pectinic acids. Pectins are used widely because of the excellent gel formation ability in acidsugar medium. Pectin molecules are not straight but coiled and there is less hydrogen bonding than in linear polymers like cellulose. To form a pectin gel a dehydrating agent must be present, usually sugar, and the proper amount of acid should be added. The best gel formation is obtained with pectins in which the methoxyl level has been reduced to about 8 percent. Pectins are evaluated for industrial use by pectin grades. These are the number of parts of sugar that one part of pectin will gel to acceptable firmness. Usual conditions are pH 3.2 to 3.5, sugar 65 to 70 percent and pectin 0.2 to 1.5 percent. Commercial grades vary from 100 to 500. Rapid set pectin has a degree of methoxylation of 70 percent or higher. This type will form gels with sugar and acid at pH optimum of 3.0 to 3.4. Slow set pectin has a degree methoxylation of 50 to 70 percent and forms gels with sugar and acid at pH optimum of 2.8 to 3.2 and at lower temperature than rapid set pectin. Low methoxyl pectins have methoxylation levels of less than 50 percent and do not form gels with sugar and acid but they will gel with calcium ions.